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July 26, 2010

Dark Matter Project May Relocate To SNOLAB

by Sam Savage

Scientists leading an underground experiment to discover dark matter may be forced to relocate to a location even deeper below the Earth's surface, according to recent BBC News reports.

Cosmic rays are to blame for disrupting the Cryogenic Dark Matter Search II (CDMS II) project, according to BBC Science Reporter Paul Rincon. The CDMS II experiments are currently taking place the Soudan mine in Minnesota, but could be relocated to the SNOLAB facility near Sudbury, Ontario, Canada.

As said rays strike the Earth, they "could completely mask the rare dark matter events sought by the experiment," says Rincon. "Team members want to cut out as much of this cosmic ray interference as possible, even if it means moving the experiment 2km below ground."

Scientists believe that more than 80-percent of matter in the universe is dark matter, meaning that is cannot emit or reflect light. The existence of dark matter has never been officially proven, but its existence "has been inferred through the gravitational pull it exerts on luminous galaxies and stars," says Rincon.

One popular theory is that this dark matter is comprised of Weakly Interacting Massive Particles (WIMPS), large numbers of which pass through the Earth every second. The CDMS II project is hoping to detect such a particle interaction, and new equipment which should be fully installed by the fall should help eliminate false positive readings, according to what team member Dr. Marek Kos of Syracuse University told BBC News on Sunday.

According to the official CDMS II website, "Using state-of-the-art cryogenic germanium and silicon detectors, the CDMS II collaboration is searching for weakly-interacting massive particles, or WIMPS, whose discovery could resolve the dark matter problem, revolutionizing particle physics and cosmology"¦ Should the dark matter of the universe consist of unidentified particles, our solar system and our planet would be passing through a flux of these dark matter particles which constitute the dark halo of the Milky Way galaxy."

"The CDMS experiments aim to measure the recoil energy imparted to detector nuclei through neutralino-nucleon collisions by employing sensitive phonon detection equipment coupled to arrays of cryogenic germanium and silicon crystals. The phonon signals generated within the crystal detectors can be processed and interpreted with information about known background rates. If found, a confidently identified above-background event rate would be analyzed to determine the nature of the responsible interaction -- perhaps enabling an identification of WIMPs," the website adds.